The present invention relates generally to an apparatus and method for controlling paper feeding in a printer, and, in particular, to an apparatus and method for controlling the paper sheet feeder of a printer utilizing signals from a paper presence detecting sensor.
In a conventional printer it is not possible to print characters on all of the lines extending from the upper edge of each individual sheet to the bottom edge of each individual sheet. This arises because positioning and placing of the individual sheet is insufficient at the extreme top and extreme bottom of each individual sheet to allow accurate printing. This results in a limited printing range which excludes several lines at the top and several lines at the bottom of each individual sheet. Conventional printing outside the print region results in lines of inferior print quality.
Accordingly, printing with the conventional printer necessitates confirmation and pre-setting of the print region prior to printing if an individual sheet feeder is used. When the print position becomes lower than the lower edge of the print region, the individual sheet is ejected and a new individual sheet is introduced to the printer. The lower end of the print region is determined as either a predetermined printing position or a position determined based upon signals from a paper detecting sensor located in the printer corresponding to an earlier detected paper position. Furthermore, when characters are printed on individual sheets utilizing software in conjunction with a personal computer, such as a wordprocessor (hereinafter referred to as application software), it is necessary to input the number of possible print lines with respect to the size of each individual sheet. Accordingly, in a conventional personal computer printer, the paper feeding condition is controlled by this inputted value.
In conventional sheet feed devices, printing problems will occur when there is a difference between the length of page controlled by the application software, in other words the length of the calculated print region and the actual length of the page controlled by the printer. Such a condition results in a failure to eject the individual sheet at the correct position and at the correct time.
The page length may be preliminarily set for the printer; however, once power is introduced to the printer, the set page length must generally be maintained. The maintained page length value is almost longer than the actual length of the individual sheet. Therefore, the value for the page length must be determined and controlled by a signal from a paper detecting sensor. However, the use of conventional paper detecting sensor mechanisms result in variations of the calculated page length value due to inaccuracies of the paper feeder mechanism, inaccuracies of the paper detecting sensor and variations of the size of individual sheets.
Accordingly, it is desired to provide an individual sheet feeding mechanism which overcomes the disadavantages of the prior art devices described above by synchronizing the page length value controlled by the printer with the page length value controlled by the application software.